BT Smart Hub + Business Smart Hub Constantly Drops WiFi & Assigns Multiple IPv6 addresses on iPhone

[simple_solution]

The following happens on apple phones w/any iOS versions including most recent devices & iOS system. 

#1: Over the past two years in EACH and EVERY case apple smart phones specifically but not iPads, desktops, laptops, etc, that are placed literally 2 feet from our router are loosing WiFi connections ( throughout the day ) sometimes as many as 10 to 20x a day while other devices on the network ( non apple phones, laptops, consoles, device, etc,  ) are just fine - no loss of connection. Messages will pop up on iPhones saying: 
   - Cannot connect to < network name > 
   - password is incorrect for < network name >
   - Unable to join the network < network name >
   - connection error < network name >

This then requires a person to go into settings, disconnect and then reconnect and where sometimes this has to be done 2 or 3x before a connection is solid. At this time, no other interruptions are happening on any other device connected to the same router. More specifically we have had multiple BT Smart Hub + BT Smart Business Hub routers so it's not just one device, it's happening with ANY router sent and on ANY iPhone connected to these routers. 

#2: These same apple phones ( and we have tried this with many iPhones, new, old, etc,  ) will also have ( in their Settings --> Wifi --> info icon --> ipV6  section ) multiple, and this means two, three, sometimes even FOUR ipV6 addresses assigned to ONE device at a time. We can't find any way to stop this from happening. More with ANY other router on any other network ( BT routers included ) there is only ONE ipV6 address assigned to the same phones that  our BT routers are assigning multiple ipV6 addresses to automatically. FYI: we are only running ONE router. There is no linking, bridging etc., the above was just to describe that in fact no matter what we do, with just ONE router running there are multiple ipV6 addresses are being assigned to iPhones when on our network. 

There is just no reason for either #1 or #2 to be happening so this must be some easy fix I'm missing. 
Any help would be greatly appreciated. 

[licquorice]

See https://community.bt.com/t5/Home-setup-Wi-Fi-network/Private-Address-MAC-Randomisation-IOS14-Apple-d...

[simple_solution]

@licquorice  thanks very much for the link. 

Unfortunately: 
   1) this does not address multiple IPv6 addresses as the IPv6 issue is not related to MAC address

   2) in this link it says  that for the "  iOS14 launch, which commences today 16th September 2020 ....  Within this iOS release, there will be new functionality within the ‘wireless settings’ that customers will be automatically opted into called ‘Private Address’. " which is great but this is happening with iPhones only on this network ( with either a normal BT smart hub or a BT Business Smart Hub ) assigning multiple ipv6 addresses ( 2, 3 sometimes 4 ) to EACH iphone connected to said network. but not non iPhone devices. More specifically this is not happening with other apple  products: iPads, MacBooks, Mac or PC desktops etc... ONLY iPhones so...

   3) the above link does not help or is related to private addresses, etc., and this does not happen on ANY other wireless with the exact same iPhone used in this example ( even when using someone's BT network with a BT Smart Hub or a BT Business Smart  Hub ) so clearly there is something else going on here with this specific network ? Can this be at the main switch or at a local switching center ? 

Furthermore,

   4) you might have left off some specific detail why iPhones ( of ANY iOS version, not just iOS 14 ) are dropping and unable to connect when 2 feet find front of the router as this is not related to the above as far as I can see . This was happening well before the iOS 14 updates took place. It's always been the case on this network with any iPhone used on it. 

What are other solutions, etc., as setting a specific MAC address, renaming these devices, etc. is not the solution as after doing what the instructions said, no changes took place: the same was happening: constant drops and multiple IPv6 addresses

Any help will be greatly appreciated. 

[licquorice]

IPv6 is different to IPv4, it is normal to get 3 addresses Global Unicast, Unique local and Link local.

[simple_solution]

@licquorice  thanks again for the response but: 

   1) yes, IPv6 is different to IPv4 however why would this NOT take place with the iPhones on other BT Smart Hub & Business Smart Hub's where there is only one address? 

   2) why would ( on this network ) there be 2, 3 or more randomly set IPv6 addresses and ONLY on iPhone devices given the above ? If there a 3 then it should be 3 all the time, not, 2 or 4 randomly and in fact today it happens to be only 2. Last week it was 3 then 2. a week previous it was 4 IPv6 address per iPhone. 

   3) to my knowledge there is no way to force IPv4 only for devices on a network ( and which we would have done ) to elevate this specific problem. Ipv4 is much more effective from our experience. In fact, for some reason you can't  even restrict a BT Smart Hub or Business Smart Hub routers to ONLY use IPv4? This itself makes no sense

But more specifically 

   4) while even writing this response, I've seen the network drop the connection to multiple iPhones ( some with iOS 14 and some not ) which makes no sense. In fact, at one point ( and again while writing this ) after the connection was dropped a message popped back up saying " could not connect to the network ) and the iPhone is 2 feet from the hub. I then had to disconnect ( from the iOS iPhone control panel ) 3x and finally it connected. 

The above seems to indicate something is specifically wrong with this line from the switch or regional fiber distribution center ? There seems to be no other explanation that I can find and of course, many thanks for your great suggestions so far

[licquorice]

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@simple_solution wrote:

@licquorice  thanks again for the response but: 

   1) yes, IPv6 is different to IPv4 however why would this NOT take place with the iPhones on other BT Smart Hub & Business Smart Hub's where there is only one address? 

No idea, all my Android and Windows devices have 3 addresses.

   2) why would ( on this network ) there be 2, 3 or more randomly set IPv6 addresses and ONLY on iPhone devices given the above ? If there a 3 then it should be 3 all the time, not, 2 or 4 randomly and in fact today it happens to be only 2. Last week it was 3 then 2. a week previous it was 4 IPv6 address per iPhone. 

Agree it should be 3 all the time, the problem appears to be with the iPhone

   3) to my knowledge there is no way to force IPv4 only for devices on a network ( and which we would have done ) to elevate this specific problem. Ipv4 is much more effective from our experience. In fact, for some reason you can't  even restrict a BT Smart Hub or Business Smart Hub routers to ONLY use IPv4? This itself makes no sense

There certainly is on Windows devices, simply disable IPv6. However, it doesn't appear to be possible on Android and also I suspect iPhones

But more specifically 

   4) while even writing this response, I've seen the network drop the connection to multiple iPhones ( some with iOS 14 and some not ) which makes no sense. In fact, at one point ( and again while writing this ) after the connection was dropped a message popped back up saying " could not connect to the network ) and the iPhone is 2 feet from the hub. I then had to disconnect ( from the iOS iPhone control panel ) 3x and finally it connected. 

The above seems to indicate something is specifically wrong with this line from the switch or regional fiber distribution center ? There seems to be no other explanation that I can find and of course, many thanks for your great suggestions so far

No, it indicates a problem between your iPhone and the hub.

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I suggest you try a factory reset of the hub (remember to turn off Smart Setup afterwards) and disable Private address MAC randomisation on the iPhones.

[simple_solution]

@licquorice  thanks again as your reply is very specific and spot on, however

re: #3: am I also correct that there is no way to disable ipV6 on BT Hubs? It was standard before & now it seems to be gone: ipV6 is always enabled and cannot be shut off ? EVERY other router on the market seems to allow this but BT does not for some reason ? 

re: #4 above: this would only be the case IF it were an issue with ONE particular iPhone but that is not the case. iPhones taken to other BT  Smart Hub & Business Smart Hub locations ( friends, family, workplaces ) do not have this problem: NO constant dropping of signal. Also when the exact same phones are connected to these networks, there is ONE ipV6 address not 2,3,4, etc., 

Why this is confusing is that factory re-set, new devices, etc., do not stop this constant dropping but where other apple devices ( iPads, desktops, etc., ) do not have loss of signal/dropping. In each case it happening when they are ALL only 2 feet from the router box. In fact even as I'm writing this it is happening. This then shows that " a factory reset of the hub (remember to turn off Smart Setup afterwards) and disable Private address MAC randomisation on the iPhone " can not be the solution & naturally we have tried this before. 

As always very much appreciate your very technical understanding / capabilities here. 

[licquorice]

It is not possible to disable IPv6 on the hubs.

One thing you can try is to disable ULA in Advanced settings>IPv6>Configuration. You could also try setting allocation mode to stateless.

It might be worth comparing the settings of hubs where you have no problem with your hub.